html5-img
1 / 172

AFWA/XOGM

Initial Tropical Training for Satellite Analysts. AFWA/XOGM. Tropical Section. Originally produced by: TSgt Nast. Revisions by: Paul McCrone. Sources. AWS/TR-95/001 AWS TR240 NAVEDTRA 40970/40971 JTWC Forecasters Handbook NEPRF TR-85-01 Tropical Weather Course (Keesler)

brinly
Download Presentation

AFWA/XOGM

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Initial Tropical Training for Satellite Analysts AFWA/XOGM Tropical Section Originally produced by:TSgt Nast Revisions by: Paul McCrone

  2. Sources • AWS/TR-95/001 • AWS TR240 • NAVEDTRA 40970/40971 • JTWC Forecasters Handbook • NEPRF TR-85-01 • Tropical Weather Course (Keesler) • Tropical TIPS

  3. Overview • Primary Physical Controls of the Tropics • Planetary-Scale Circulation in the Tropics • Non-Severe Weather Systems and Tertiary Circulation's • Basic Analysis and Circulation Models • Monsoons • Climate Anomalies • Tropical Cyclones • Severe Weather in the Tropics • Tropical Forecasting

  4. Primary Physical Controls of the tropics • Earth’s Energy Budget • Effects of Land-SeaDistribution • Terrain Effects • Diurnal Effects

  5. Primary Physical Controls of the tropics

  6. AWS/TR-95/001 Page 11 Figure 2-1

  7. Earth’s Energy Budget

  8. Earth’s Energy Budget • Vertical heat transfer mechanisms • Radiation - not very significant • Sensible heat transfer • Latent heat transfer - Most important vertical mechanism in tropics • Conduction - molecular boundary layer • Convection - air warmed by conduction • Condensation (latent heat becomes sensible heat) • Evaporation (Sensible heat becomes latent heat)

  9. Earth’s Energy Budget

  10. Earth’s Energy Budget • Horizontal Heat Transfer • Horizontal heat transfer mechanisms • Sensible heat transfer through warm- or cold-air advection • About 40% of earth's total horizontal heat exchange occurs through ocean currents. • Latent heat transfer. • Moisture advection. • Latent heat release aloft, carried poleward by the Hadley cell.

  11. Earth’s Energy Budget

  12. Effects of Land-Sea Distribution • Determines climate type (monsoon, maritime, Continental.). • Max seasonal variations occurs over land. • Most convection and latent heat-sensible heat conversion takes place over land. • Land-sea breeze circulation's are a direct result.

  13. Terrain Effects • High altitude more typical of mid-latitude weather. • Rainfall: • Leeside or windward location usually most important factor. • In trade winds, heaviest rain usually on slopes just below trade-wind inversion.

  14. Terrain Effects • Whether a location is on the leeside or windward side is a very important factor Rainfall

  15. Diurnal Effects • Temperature Range • Clouds • Rainfall

  16. Diurnal Effects • Temperature Range • On small islands and coastlines 3-5°C with prevailing onshore flow. • On inland locations or coasts 5-10°C with prevailing land breeze. • In the interior in the dry season > 10°C.

  17. Diurnal Effects • Clouds • Oceans • Maximum (0400-0700L), minimum (1400L-1900L) • Land • Daytime maximum, nocturnal minimum

  18. Diurnal Effects • Rainfall • Nocturnal max over oceans, and small islands. • Shower maximum over land in afternoon. • Monsoon areas and areas in disturbances have night to early morning maximum.

  19. Planetary-Scale Circulation in the Tropics Definitions and General Characteristics Primary Weather Zone Tropical Wind Profiles Upper Tropospheric Features

  20. Definitions and General Characteristics • Classical Definitions. • Ancient Greeks - Tropics of Cancer to Capricorn (23.5N to 23.5S) • Alexander Supan - Average Annual Temp > 68 F (20°C) • Early 1900s - W.P. Koppen • World is divided into climatic Zones A to F. • A= tropical rainy, Af = rain forest, Aw = savanna, Am = monsoon.

  21. Definitions and General Characteristics • Dynamic Definitions - allow for seasonal, longitudinal variations. • Dividing line between mid-Tropospheric easterlies and westerlies (axes of STRs). H H H H H H

  22. Definitions and General Characteristics • Tropical weather characteristics • Cumulus clouds predominate. • Conditionally unstable. • Air temperatures comparable to ocean surface temperatures. • Predominately easterly low-level flow.

  23. Definitions and General Characteristics • Climatology is more important in the tropics than it is in the mid-latitudes • Weather dominated by semi-permanent, slowly migrating systems • Subtropical Ridge (STR) • Equatorial Trough (ET)

  24. Primary Weather Zones and Systems • Subtropical Ridge (STR) • Surface • Centered on five oceanic anticyclones. • Over the oceans: • shrinks and retreats equatorward in winter, grows and builds poleward in summer. (inducing TUTT formation)

  25. Primary Weather Zones and Systems • Subtropical Ridge (STR) • Surface • Axis tilts ENE-WSW in Northern Hemisphere, ESE-WNW in Southern Hemisphere. • Ridge axis normally 23-35 degrees latitude North and South

  26. Primary Weather Zones and Systems

  27. Primary Weather Zones and Systems • Subtropical Ridge (STR) • Aloft H H • Slopes to equator with height. • Position of axis at 200 mb is 15-20° latitude. H L H H H • More elongated east-west than the surface ridge.

  28. Primary Weather Zones and Systems • Trade-wind region • Region of low-level prevailing easterlies between STR and ET. • NE trades in Northern Hemisphere, SE trades in Southern Hemisphere. • General subsidence with capping trade-wind inversion.

  29. Equatorial Trough (ET) • Other terms • Near equatorial trough (NET). • ITCZ or ITC. • Doldrums. • Meteorological or thermal equator. • Near-equatorial Tradewind Convergence (NETWC).

  30. Equatorial Trough (ET) • Location, strength, circulations vary • Generally found where trade winds from each hemisphere converge • Low pressure from heating and upward motion • May be axis of convergence or series of cyclones

  31. Equatorial Trough (ET) • Several streamline configurations: • Near Equatorial Convergence Zone (or trade-wind trough). • Monsoon trough • Confluent westerlies. • Equatorial Buffer Zone

  32. (ET) Streamline Configurations • Near Equatorial Convergence Zone (or trade-wind trough). • Confluent zone between trade winds of each hemisphere. • Usually over oceans, but can extend over adjacent land areas.

  33. Trade Wind Trough

  34. (ET) Streamline Configurations • Monsoon trough • Often a series of cyclonic centers: • Heat lows (over land primarily). • Thunderstorm clusters, non developing. • Monsoon depressions. • Tropical disturbances.

  35. (ET) Streamline Configurations • Monsoon trough • Locations • Africa - Sub-Sahara in July and Kalahari-Madagascar in January. • Central America - East Pacific: south of Central America all year and occasionally crosses into Caribbean.

  36. Africa - Sub-Sahara in July

  37. (ET) Streamline Configurations • Monsoon trough • Locations • South Asia - West Pacific: Iraq to northern India through SE Asia to Guam. • Australia - along the northern coast from December through February.

  38. (ET) Streamline Configurations • Confluent westerlies. • Locations: • West of Central America in fall. • NW of Australia in Southern Hemisphere summer. • Winds generally light, speed convergence increasing downstream.

  39. H H (ET) Streamline Configurations H H Monsoon Trough C C Confluent Westerlies Tradewind Trough H

  40. (ET) Streamline Configurations • Equatorial Buffer Zone • July: • Southern Hemisphere SE winds become SW entering monsoon trough. • Equatorial Buffer Zone • January: • Northern Hemisphere NE winds become NW entering Southern Hemisphere monsoon trough.

  41. B (ET) Streamline Configurations • Equatorial Buffer Zone • Buffer Cells • Weak, closed circulations near equator where curving winds "cut off". • No net inflow or outflow. • Labeled with a "B" on streamline analysis.

  42. Tropical Vertical Wind Profiles: Deep Easterlies • Low-level east winds remain easterly with height • Found within 15° of equator • May extend to 30° in summer hemisphere • Not in all seasons or regions • Narrowest north-south extent at 200 mb

  43. Tropical Vertical Wind Profiles: Shallow Easterlies • Shallow Easterlies • Low-level easterlies become westerly with height • Average 15-30° latitude, closer to equator in winter hemisphere • Example - Hawaiian islands (20°N) in shallow easterlies all year

  44. Tropical Vertical Wind Profiles: Shallow Westerlies • Low-level westerlies become easterly with height. • Found in monsoon regions in summer. • Examples: western Pacific, Indian Ocean, western Africa (shallower in Africa).

  45. Upper-Tropospheric Features • Subtropical Jet (STJ) • Found 20-35°N and 25-32°S (average). • Causes • Upward branch of Hadley cell circulation. • Conservation of angular momentum accelerates air to east as it moves north.

  46. Sub Tropical Jet

  47. Upper-Tropospheric Features • Tropical Easterly Jet (TEJ) • Feature of northern hemisphere (NH) summer monsoon in Asia • Very persistent in NH summer months • Location: central Africa to SE Asia (from 5 degrees to 20 degrees North latitude) • Strongest winds (80-100 kts) over Arabian Sea between 40,000-55,000 ft (200-100 mb). Highest observed winds: 152 kts

More Related